body{
    padding: 0;
    background: black;
    
    /* overflow: hidden; */
    height: 100vh;
    display: flex;
    /* 盒子轴居中 */
    align-items: center;
    /* 盒子居中留白 */
    justify-content: space-around;

}

.enclose{
    /* 相对于正常位置进行定位 */
    position: relative;
    color: white;
    width: 150px;
    height: 50px;
    background: rgb(90, 90, 90);
    text-align: center;
    cursor: pointer;
    /* 文本阴影 */
    text-shadow: 0 0 1px cyan;
    line-height: 50%;
    font-size: 20px;
}

.enclose:hover{
    text-shadow: 0 0 10px cyan;
}

.top,
.right,
.bottom,
.left{
    position: absolute;
    background: cyan;
    box-shadow: 0 0 10px rgb(167, 245, 255);
   /* a渐变 */
    transition: all .1s;
}

.top{
    top: 0;
    left: 0;
    width: 0;
    height: 3px;
    transition-delay: .3s;
}
.enclose:hover>.top{
    width: 150px;
    transition-delay: 0s;
}

.right{
    top: 0;
    right: 0;
    width: 3px;
    height: 0px;
    transition-delay: .2s;
}
.enclose:hover>.right{
    height: 50px;
    transition-delay: .1s;

}


.bottom{
    bottom: 0;
    right: 0;
    width: 0;
    height: 3px;
    transition-delay: .1s;
}
.enclose:hover>.bottom{
    width: 150px;
    transition-delay: .3s;

}

.left{
    bottom: 0;
    left: 0;
    width: 3px;
    height: 0px;
    transition-delay: 0s;
}
.enclose:hover>.left{
    height: 50px;
    transition-delay: .4s;

}

/* 色调旋转属性 */
div:nth-child(1){
    filter: hue-rotate(290deg);
}
div:nth-child(2){
    filter: hue-rotate(180deg);
}
